Apparatus for forming valve tappets and the like



Nov. 10, 1925- 7 1,560,832

- H. '8. LEE

APPARATUS FOR FORMING VALVE TAPPETS AND THE LIKE Filed Nov. 27, 1922 Patentecl Nov. 1 0, 1925.

UNITED STATES PATENT OFFICE.

, HARRY s, LEE, or PLYMOUTH, MICHIGAN, AssIeN'oR r MERRILL M. wILoox, or

' SAG-INAW, mrcnreau. 3

APPARATUS FOR FORMING VALVE TAPPETS AND THE II'IKE.

Application filed November 27, 1922. Serial No. 603,632.

certain new and useful Im'provem-ents=- in Apparatus for Forming Valve Tappets and the like, of. which the following is a specification, reference being had therein'to the 1 accompanying drawings.

The invention relates to the methodand apparatus for forming chilled faces onrc'ast' metal articles and has .for its object theobtaining of more uniform and satisfactory results. In particular, it is'an object ofthe invention to provide for accurately predetermining the lat ral extent and the depth of the chilled or hardened metal and for producing any desired variation. For instance, in the forming ofvalve tappets, it IS desirable to have the center of the tappet hardening effect towards the periphery. Such a resultcan be easily obtained by my 2 improved method aiid apparatus.

While my invention is applicable to the production of various articles, I shall specifically describe it as designed for the manu facture of valve tappets.

In the drawings:

Figure 1 is a cross-section through the apparatus;

Figure 2 is a bottom plan view thereof.

As specifically shown, the members to be formed have cylindrical shanks A with enlarged heads B provided withflat bearing faces C, which are to-be' chilled and hardened.

As is well understood, the hardening of 40 the metal is produced by the-rapid cooling and the effect of a chill, which forms a portion of the molding surface, is to thus rapidly dissipate the heat. The, rate of heat dissipation is de endent upon several factorst including t e mass, the specific heat and thermo-conductivity of the material forming the chill and the amount of radiating surface. 'I have discovered that by properly fashioning the chill, any desired ;difl'erential chilling effect -may be produced,

and the construction preferably used is one 7 in which the greatest depthv of hardening is at .the center of the surface C, from which point the hardening is preferably decreased towards the periphery. In detail, the chill D is preferably formed of a metallic plate which is of suflicient area to register with a plurality of mold cavities.

Opposite each of these cavities the depth of the metal inthe chill is increased beneath the center of the cavity, as indicated at E,

d minishing therefrom progressivelyv towards the periphery. If it is desired .to

leave the peripheral portion of the member in an unchilled condition, this may be accomplished by forming an annular groove F in the chill face, which groove may be filled with a material low in thermo-conductivity such as the ordinary core material. With the construction as shown, the plate D is placed in the mold flask so as to form the bottom of all of the mold cavities. hen the 'molten' metal is poured into the mold cavities, the rate of heat dissipation will be of greatest hardness and to diminish this greatest at the center, for the reason that elfect will depend upon .theshape of the por- 30 .ftion E. Preferablythis portion is of oval form, which I have found from produces satisfactory results.

Where'the grooves filled with core materialare used, the peripheral portion of the 35 face will be left unchilled and the hardening will gradually increase from the inner edge of the groove towards the center of the chill.

Another important advantage of my improved method is that I am'enabled to secure uniform results in hardening where heretofore there has been considerable variation. For instance, it frequently happens that where a chill extends comple'tel across the mold cavity, the chilling or bar ening efi'ect will sometimes extendp-nly part way. The reason for this I do not fully understand, but I. have discoveredthat b placing heat insulating material about t e eriphery, perfect. uniformity is obtained insuccessive castings.

What I claim as my invention is: I 1. Ina mold, an apparatus for forming disk-shaped tappets and the like having differentially hardened surfaces, comprising a flat chill plate forming one faoeof the mold practice cavity, said chill plate having a projection thereon, said projection greatest in depth op-v -posite that portion of said tappet disk to Y which is imparted the greatest depth of chill and of less depth opposite that part of sai disk to which is imparted a lesser depth of chill."

' 2. In a mold, an apparatus for forming tappets having differentially hardened surfaces comprising a chill plate forming one face of the mold cavit said chill plate having projections thereon, said project-ions greatest in depth oppositethe center of the chilling surface, diminishing in depth from this point toward the peripher an annular groove in said chill plate adjacent the ,periphery of said projection.

the periphery.-

forming a molding face oneach, said chill plate being provided with projections onthe side opposite and registering with the respective cavities, said projections fashioned to produce chilling from the center towards the periphery of said disk faces.

' 4, In a mold, an apparatus for forming valve tappets and the like having chilled I hardened disks in which the greatest depth 7 of hardening is at the center of the disk and decreases toward the periphery, said, apparatus comprising a chill plate forming one wall :of the mold cavity,- a chill projection on the 7 side of the plate opposite the cavity, the'projection having its greatest mass opposite the center of the chilling surface and diminishing in mass from this point towards In testimony hereof Iafiix my signature,

HARRY S. LEE. 

